Method of isolating a downhole zone for the gathering of data

ABSTRACT

A downhole tool including an inner mandrel, a first sealing element disposed around the inner mandrel, a second sealing mandrel disposed around the inner mandrel and axially below the first sealing elements, and a monitoring device disposed on the downhole tool between the first and second sealing elements. Also, a method of monitoring a downhole formation, the method including disposing a downhole monitoring tool in a wellbore, isolating a first production zone from a second production zone, wherein the first production zone is axially above the second production zone, and monitoring a condition of the first production zone.

CROSS-REFERENCE TQ RELATED APPLICATION

This application, pursuant to 35 U.S.C. §119(e), claims priority to U.S. Provisional Application Ser. No. 61/165,792 filed Apr. 1, 2009. That application is incorporated by reference in its entirety.

BACKGROUND

1. Field of the Disclosure

Embodiments disclosed herein relate generally to downhole tools for monitoring a first production zone while producing from a second production zone. More specifically, embodiments disclosed herein relate to downhole tools and methods of using downhole tools for isolating a first production zone from a second production zone, and producing from the second production zone while monitoring the first production zone.

2. Background Art

The control of oil and gas production wells constitutes an on-going concern of the petroleum industry due, in part, to the enormous monetary expense involved, in addition to the risks associated with environmental and safety issues. Production well control has become particularly important and more complex due to the various environments and formations in which drilling is performed. There is a need for controlling zone production, isolating specific zones, and otherwise monitoring each zone in a particular well.

In certain geographic locations local regulations require the collection of data from a wellbore, such as in the production of coal bed methane. In order to collect the required data, the zone of interest, from which the coal bed methane is being produced, must be isolated to allow a build up of methane, such that the downhole condition of the production zone may be monitored. Typically, coal bed methane wells include many production zones, and at different times, one or more of the zones may require data acquisition in order to comply with local regulations.

In order to obtain the necessary data, an operator typically closes off a particular zone, disposes a data acquisition device in the desired production zone, and then collects data from the production zone for a required time period. Depending on the particular geographic location, the zone may require data collection for extended periods of time, for example 14 days or more. During the 14 days, the well is effectively shut in, and no hydrocarbons are produced therefrom. As a result of shutting in the well for the required period of time, the payback period for the well investment is extended.

Accordingly, there exists a need for downhole tools for monitoring a first production zone while producing from another production zones of a well.

SUMMARY OF THE DISCLOSURE

In one aspect, embodiments disclosed herein relate to a downhole tool including an inner mandrel, a first sealing element disposed around the inner mandrel, a second sealing mandrel disposed around the inner mandrel and axially below the first sealing elements, and a monitoring device disposed on the downhole tool between the first and second sealing elements.

In another aspect, embodiments disclosed herein relate to a method of monitoring a downhole formation, the method including disposing a downhole monitoring tool in a wellbore, isolating a first production zone from a second production zone, wherein the first production zone is axially above the second production zone, and monitoring a condition of the first production zone.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial cross sectional view of a top portion of a downhole tool according to embodiments of the present disclosure.

FIG. 2 is a partial cross sectional view of a middle portion of a downhole tool according to embodiments of the present disclosure.

FIG. 3 is a partial cross sectional view of a lower portion of a downhole tool according to embodiments of the present disclosure.

FIG. 4 is a cross sectional view of a cap of a downhole tool according to embodiments of the present disclosure.

FIG. 5 is a cross sectional view of a monitor carrier body of a downhole tool according to embodiments of the present disclosure.

FIGS. 6 and 7 are cross sectional views of an upper portion and a lower portion of a downhole tool, respectively, disposed within a wellbore according to embodiments of the present disclosure.

FIGS. 8 and 9 are cross sectional views of an upper portion and a lower portion of a downhole tool monitoring a first production zone while producing from a second production zone according to embodiments of the present disclosure.

FIGS. 10 and 11 are cross sectional views of an upper portion and a lower portion of a downhole tool prior to removal from a wellbore according to embodiments of the present disclosure.

FIGS. 12 and 13 are cross sectional views of an upper portion and a lower portion of a downhole tool during removal from a wellbore according to embodiments of the present disclosure.

FIG. 14 is a schematic representation of a downhole tool disposed in a wellbore according to embodiments of the present disclosure.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate to downhole tools for monitoring a first production zone while producing from a second production zone. More specifically, embodiments disclosed herein relate to downhole tools and methods of using downhole tools for isolating a first production zone from a second production zone, and producing from the second production zone while monitoring the first production zone.

Embodiments disclosed herein may thus provide downhole tools capable of recording conditions in a production zone in a wellbore while continuing to produce from additional production zones. By selectively isolating certain sections of a wellbore, conditions within such isolated section of the wellbore may be recorded and/or monitored in real time. As used herein, real time refers to data processing that delivers outputs as the outputs become available. As such, real time is not intended to require that the return of the outputs is instantaneous. Recording devices refer to devices capable of receiving data relating to a condition of a wellbore and storing such data on writable media. The media may then be read at a later time, such as by attaching the recording device or recordable media to a computer located at the surface of a drill site.

Referring to FIGS. 1-3, a partial cross-section of downhole tool 100 according to embodiments of the present disclosure is shown. FIG. 1 viewed left to right illustrates a top portion of the downhole tool 100, while FIG. 2 illustrates a middle portion of the downhole tool 100, and FIG. 3 illustrates a bottom portion of the downhole tool 100. In this embodiment, downhole tool 100 includes an inner mandrel 32, a middle mandrel 19, and an outer mandrel 18. The inner mandrel 32 provides a central flow conduit through the entire length of downhole tool 100. Middle mandrel 19 is disposed around inner mandrel 32 and outer mandrel 18 is disposed around middle mandrel 19. In certain aspects, outer mandrel 18 may be disposed around middle mandrel 19, such that middle mandrel 19 and outer mandrel 18 do not directly contact one another.

Downhole tool 100 also includes first and second sealing elements 34 and 35, respectively. In this embodiment, first and second sealing elements 34 and 35 each include a first seal 13 and a second seal 15. First seal 13 of sealing elements 34 and 35 may be an expandable material, such as an elastomeric material having a hardness of, for example, 80 durometers. Second seal 15 of sealing elements 34 and 35 may also be an expandable material, such as an elastomeric material having a hardness of, for example, 70 durometers. Those of ordinary skill in the art will appreciate that sealing elements 34 and 35 may be formed from various types of seals 13 and 15 used in packers, as is known in the art. As such, seals 13 and 15 may be formed from other elastomeric materials having various hardness ratings.

As illustrated, sealing elements 34 and 35 are disposed around downhole tool 100. The axial distance between first sealing element 34 and second sealing element 35 defines a variable straddle. In certain embodiments, the variable straddle of downhole tool 100 may be between about 1 and 4 meters, while in other embodiments, the variable straddle may be between 2 and 3 meters. The variable straddle may thereby also define the distance a wellbore is isolated when sealing elements 34 and 35 are actuated. The actuation of downhole tool 100 causes sealing elements 34 and 35 to radially expand as seals 13 and 15 are compressed. One method of radially expanding seals 13 and 15 is described in detail below.

When the downhole tool 100 is lowered into a wellbore to a desired depth, an operator may anchor and set downhole tool 100 to the inner wall of the wellbore. In this embodiment, the tool is anchored by expanding a slip assembly 36, which includes a slip cage 30, a slip spring 29, and a slip 28. To expand the slip 28 and anchor downhole tool 100 to the wellbore, an upper cone 25 is moved axially upward thereby radially displacing slip 28, as slip 28 contacts both lower cone 31 and upper cone 25. Such radial displacement pushes slip 28 radially outward and into contact with the wellbore or a casing of a wellbore disposed therein. The expansion of slip 28 may thereby anchor downhole tool 100 within the wellbore, such that subsequent operations will not axially move downhole tool 100 within the wellbore.

After downhole tool 100 is anchored in the wellbore, the operator may set downhole tool 100, thereby isolating a section of the wellbore. To set downhole tool 100, the operator may displace outer mandrel 18 axially downward, while holding middle mandrel 19 in place. Such relative axial displacement of outer mandrel 18 and middle mandrel 19 may thereby engage teeth (not shown) of ratchet sub 10, thereby holding outer mandrel 18 and middle mandrel 19 in a position approximately equal to the amount of axial displacement. As outer mandrel 18 moves axially downward, seals 13 and 15 of sealing elements 34 and 35 are compressed, and as a result of the compression, radially expanded. Those of ordinary skill in the art will appreciate that second sealing elements 35 may radially expand before first sealing element 34. However, in other embodiments, first and second sealing elements 34 and 35 may radially expand in alternating order, or alternatively, may radially expand at approximately the same time. After sealing elements 34 and 35 are radially expanded, and in contact with the wellbore or casing, a section of the wellbore may be isolated.

Downhole tool 100 also includes a monitoring device 37. Monitoring device 37 may include one or more sensors configured to monitor temperature, pressure, chemical compositions (e.g., water, hydrogen sulfide, or carbon dioxide), or other conditions that may exist in a particular production zone. As illustrated, monitoring device 37 is disposed in a monitor carrier body 23. Monitor carrier body 23 may include a cylindrical tube into which the monitoring device 37 may be disposed. Monitor carrier body 23 may be formed from metal, such as stainless steel, or plastic, and depending on the specific condition being monitored, may include perforations in the monitor carrier body 23. Monitor carrier body 23 may be configured to receive a cap 20, which may be threaded onto monitor carrier body 23 after monitoring device 37 is disposed therein. In certain embodiments, cap 20 may be held in place on monitor carrier body 23 with a set screw 21. To secure monitor carrier body 23 to downhole tool 100, one or more straps 22 may be used to hold monitor carrier body 23 around outer mandrel 18.

Referring briefly to FIGS. 4 and 5, a close cross sectional view of a cap 20 and a monitor carrier body 23 according to embodiments of the present disclosure is shown. As illustrated, cap 23 may include a cap receiving slot 38 that corresponds to a body receiving slot 39 on monitor carrier body 23. When cap 23 is placed over monitor carrier body 23, a pin (not shown) or screw may be inserted through cap receiving slot 38 and body receiving slot 39 to hold the cap in place. In other embodiments, a pin may not be required, as the cap may be threadable.

Referring back to FIGS. 1-3, in alternate embodiments, outer mandrel 18 may include a slot (not shown) for receiving monitor carrier body 23. The slot may be integrally formed as a depression in outer mandrel 18, such that monitor carrier body 23 may be disposed therein. The slot may thus hold monitor carrier body 23 in place as downhole tool 100 is run in or out of the wellbore. Those of ordinary skill in the art will appreciate that in certain embodiments, monitoring device 37 may be directly secured to downhole tool 100, without use of a monitor carrier body 23, depending on the specific type of monitoring device 37 and/or application in which the device is used. Downhole tool 100 may also include multiple monitoring devices 37 disposed around outer mandrel 18. For example, in certain embodiments, downhole tool 100 may have two, three, or more monitoring devices 37. Each monitoring device may include a single sensor, or may include multiple sensors, thereby providing more information about the condition in the production zone, or in certain embodiments, providing redundant information to an operator.

Downhole tool 100 may also include other various components, such as multiple shear screws 4 or shear pins, which allow an operator to disengage the downhole tool with the wellbore or casing. For example, when an operator determines that the downhole tool should be removed from the wellbore, a jarring device or slickline (not shown) may engage downhole tool 100, providing an upward force, effectively shearing shear screws 4. When shear screws 4 are sheared, compression of sealing elements 34 and 35 is relaxed as lower cone 31 disengages a collet mandrel 26. Lower cone 31 thus becomes unsupported after upward movement of main mandrel 32. Fingers (not shown) of collet mandrel 26 collapse radially inward, releasing upper cone 31, and lower cone 31 falls downward, thereby allowing slip 28 to move radially inward. Additionally, shearing shear screws 4 may release slip 28, thereby disengaging downhole tool 100 from the wellbore or casing. After the downhole tool 100 is disengaged from the wellbore or casing, the operator may retrieve downhole tool 100 using, for example, wireline, coiled tubing, or jointed pipe.

Various methods of setting downhole tool 100 may also be used. For example, in certain embodiments, when the downhole tool 100 is lowered into the wellbore, the downhole tool 100 may be coupled to a wireline adapter (not shown), which engages downhole tool 100 at an upper end 1. The wireline adapter may be coupled to downhole tool 100, and provide a connection to a setting tool (not shown). The setting tool may be, for example, a hydraulic, pressure, or mechanical setting tool. In certain embodiments, the setting tool may provide an explosive, such that actuation of the explosive applies a pressure to the downhole tool 100, thereby expanding the sealing elements 34 and 35 as described above. At a predetermined force (e.g., 35,000 pounds) a tension stud from the wireline adapter breaks away, thereby releasing the wireline adapter from the downhole tool 100, such that the setting tool and wireline adapter may be retrieved from the wellbore on, for example, a wireline.

Downhole tool 100 may also include various features for running the tool on wireline. For example, downhole tool 100 may include a reentry sub 33 configured to guide wireline into position within downhole tool 100, as downhole tool 100 is disposed in a wellbore. Additionally, downhole tool 100 may include a sliding sleeve (not shown) between first and second sealing elements 34 and 35. In such an embodiment, a port (not shown) configured to provide fluid communication between the production zone and inner mandrel 32 may also be disposed on downhole tool between first and second sealing elements 34 and 35. Such an embodiment would allow an operator to selectively produce from the isolated formation by actuating the sliding sleeve, thereby either opening or closing the port. Thus, depending on the requirements of the monitoring operation, prior to retrieving downhole tool 100 from the wellbore, an operator may produce from the isolated production zone. Alternatively, in embodiments using real time monitoring devices, when sufficient data is collected, the operator may open the port, thereby allowing production from the isolated zone to resume.

Referring to FIGS. 6-13, an operational sequence according to embodiments of the present disclosure is shown. Specifically, FIGS. 6 and 7 illustrate running a downhole tool into a wellbore, FIGS. 8 and 9 illustrate setting the downhole tool and using the downhole tool, FIGS. 10 and 11 illustrate disengaging the downhole tool from the wellbore, and FIGS. 12 and 13 illustrate retrieving the downhole tool from the wellbore.

Referring specifically to FIGS. 6 and 7, a downhole tool 100 is illustrated being disposed in a wellbore 101 on a wireline 102. Downhole tool 100 includes a top portion 110 located at an axially upward location and relatively closer to the surface of wellbore 101 than bottom portion 120, which is located axially downward and relatively close to the bottom of the wellbore. Downhole tool 100 also includes a setting tool 125 coupled to a wireline adapter 130, which allows downhole tool 100 to be lowered into the wellbore 101 on wireline 102. In alternate embodiments, downhole tool 100 may be lowered into wellbore 101 on coiled tubing or jointed pipe.

Downhole tool 100 further includes first and second sealing elements 34 and 35 in an unexpanded state, and an anchor 104, also in an unexpanded state. As downhole tool 100 is lowered into wellbore 101, an operator may monitor the location of downhole tool 100 within the wellbore 101. When downhole tool reaches a desired location, such as a first production zone, anchor 104 may be set, and sealing elements 35 and 35 radially expanded into contact with wellbore 101, as explained above.

Referring to FIGS. 8 and 9, downhole tool 100 is illustrated disposed in wellbore 101 across a formation of interest, i.e., a first production zone 140. As illustrated, downhole tool 100 includes an anchor 104 engaged with wellbore 101, thereby preventing axial movement of downhole tool 100 within wellbore 101. Sealing elements 34 and 35 have also been radially expanded into contact with wellbore 101 or casing, thereby isolating first production zone 140 from a second production zone located below first production zone 140. Because first production zone 140 is isolated from second production zone, a monitoring device 37 disposed on downhole tool 100 may be used to monitor a condition of the first production zone 140. As illustrated, downhole tool 100 may include multiple monitoring devices 37; in this embodiment two monitoring devices 37 are included.

Because the downhole tool 100 is set in wellbore 101, the setting tool and wireline adapter have been disconnected from downhole tool 100 and retrieved to the surface. As such, inner mandrel 32 now provides a central flowbore, or conduit, fluidly connecting the second production zone to the surface. Inner mandrel 32 may thus be used to produce fluids, such as hydrocarbons or water, from second production zone while the condition of the isolated first production zone is monitored. Such monitoring may continue until enough data is collected, or in certain embodiments, may allow real time monitoring of conditions in the wellbore by providing a connection (not shown) to the surface.

Those of ordinary skill in the art will appreciate that in certain embodiments, downhole tool 100 may include multiple sealing elements and/or monitoring devices in addition to sealing elements 34 and 35 and monitoring device 37, thereby allowing for the isolation and monitoring of two or more production zones. As such, conditions in multiple production zones may be monitored while still allowing production from certain formations. A downhole tool 100 having a sliding sleeve and port assembly, as described above, may also be used to selectively produce from certain production zones while monitoring from other production zones. After a defined period of time, or when enough data is collected, downhole tool 100 may be removed from wellbore 101.

Referring to FIGS. 10 and 11, downhole tool 100 is illustrated with a downhole retrieval device 150 attached thereto. Downhole retrieval device 150 is illustrated jarred into inner mandrel 32, such that a subsequent upward force of the jar breaks the shear pins (not shown), thereby collapsing sealing elements 34 and 35 into an unexpanded state, and allowing downhole tool 100 to be removed from wellbore 101. In certain embodiments, a jarring device (not shown) may disposed in the wellbore and coupled to downhole retrieval device 150 to provide the axial force required to break the shear pins. In other embodiments, coiled tubing may be used to apply the necessary force to break the shear pins. Whether coiled tubing, slickline, or wireline downhole retrieval device 150 is used, the force applied to downhole tool 100 must be sufficient to shear the shear pins. Those of ordinary skill in the art will appreciate that in certain embodiments, slickline may also be used to provide the downhole force and remove downhole tool 100 from the wellbore. Because slickline has greater pulling capacity, such methods may be appropriate when greater axial forces are required to move downhole tool 100. Additionally, when inserting the wireline downhole retrieval device 150, coiled tubing, or slickline into downhole tool 100, the retrieval device 150, coiled tubing, or slickline should be stabbed into downhole tool 100 in a substantially axial direction, and pulled upwardly in the opposite direction.

Referring to FIGS. 12 and 13, downhole tool 100 is illustrated with sealing elements 34 and 35 and anchor 104 disengaged from wellbore 101, thereby allowing an operator to remove downhole tool 100 from wellbore 101. During removal, sealing elements 34 and 35, as well as anchor 104 will be expanded radially less than the diameter of the tool, thereby preventing downhole tool 100 from becoming stuck in wellbore 101 during removal. Those of ordinary skill in the art will appreciate that downhole tool 100 may be removed from wellbore 101 after the collection of sufficient data to allow for analysis of a condition of the zone of interest, or when the operator determines that sufficient data has been collected.

Referring to FIG. 14 a schematic representation of a downhole tool 100 disposed in a wellbore 101 according to embodiments of the present disclosure is shown. In this embodiment, downhole tool 100 is illustrated set in wellbore 101, as sealing elements 34 and 35 are radially expanded into contact with wellbore 101. Wellbore 101 is divided into discrete production zones, specifically, a first production zone 170 and a second production zone 180.

Downhole tool 100 also includes monitoring devices 37 for monitoring a condition of first production zone 170 and an inner mandrel 32 providing a central throughbore such that fluids may be produced from second production zone 180. As illustrated, fluids and gases 190 in first production zone 170 are isolated from second production zone 180. Thus, a condition, such as pressure, temperature, or chemical composition of the fluids and/or gases in first production zone 170 may be monitored and/or recorded. Because inner mandrel 32 extends below first production zone 170, fluids and/or gases in second production zone 180 may be produced therefrom. Thus, downhole tool 100 allows for a condition to be monitored in first production zone 170 while fluids/gases are produced from second production zone 180 below first production zone 170.

Methods of monitoring a downhole formation, according to embodiments disclosed herein may thus provide downhole tool 100 disposed in wellbore 101. First production zone 170 may be isolated from second production zone 180, such that a condition of first production zone 170 may be monitored. In certain embodiments, after the condition is monitored for a sufficient period of time through, for example, recording aspects of the downhole condition, downhole tool 100 may be retrieved from wellbore 101. In certain embodiments, rather than record a condition, the downhole tool 100 may provide for real time communication to the surface by, for example, running a communication link from the surface to downhole tool 100.

In still other embodiments, downhole tools 100 according to the present disclosure may allow for the production of a fluid from second production zone 180 such that substantially none of the fluids produced therefrom are exposed to first production zone 170. However, in certain embodiments, downhole tool 100 may allow for selective production of fluids from first production zone 170 through the use of, for example, a sliding sleeve and port, as explained above.

Advantageously, embodiments of the present disclosure may allow for production of a fluid from a production zone while another production zone is monitored. Because production from a particular production zone may continue during monitoring of another production zone, the well does not have to be shut in during the monitoring. As such, drilling operators may be better able to comply with local regulations, such as during the production of coal bed methane, without decreasing production levels from the well.

Also advantageously, the amount of revenue generated may be increased, thereby decreasing the payback period for well investment. Because the tool is removable and reusable in subsequent isolation and monitoring operations, the cost of monitoring a wellbore may be decreased, thereby decreasing the net cost of complying with local regulations in certain production operations.

While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims. 

1. A downhole tool comprising: an inner mandrel; a first sealing element disposed around the inner mandrel; a second sealing element disposed around the inner mandrel and axially below the first sealing element; and a monitoring device disposed on the downhole tool between the first and second sealing elements.
 2. The downhole tool of claim 1, further comprising: a middle mandrel disposed around the inner mandrel; and an outer mandrel disposed around the middle mandrel; wherein axially displacing the outer mandrel relative to the middle mandrel radially expands the first and second sealing elements.
 3. The downhole tool of claim 2, further comprising: an anchor disposed around the inner mandrel.
 4. The downhole tool of claim 3, wherein the anchor comprises a slip assembly, the slip assembly comprising: a slip; a slip spring; and a slip cage.
 5. The downhole tool of claim 1, wherein the inner mandrel provides a conduit between the first and second sealing elements.
 6. The downhole tool of claim 1, wherein the monitoring device comprises at least one of a temperature sensor, a chemical composition sensor, and a pressure sensor.
 7. The downhole tool of claim 1, wherein the monitoring device is disposed in a socket on the outer mandrel.
 8. The downhole tool of claim 1, further comprising: a wireline adapter disposed axially above the first sealing element and configured to engage the middle mandrel.
 9. The downhole tool of claim 8, further comprising: a setting device disposed above axially above the wireline adapter.
 10. The downhole tool of claim 1, further comprising: a port configured to provide fluid communication between a first production zone and the inner mandrel; a sliding sleeve disposed inside the inner mandrel, wherein the sliding sleeve is configured to provide selective isolation of the first production zone from the inner mandrel.
 11. The downhole tool of claim 1, wherein the axial distance between the first sealing element and the second sealing element defines a variable straddle, and wherein the variable straddle is between 1 and 4 meters.
 12. A method of monitoring a downhole formation, the method comprising: disposing a downhole monitoring tool in a wellbore; isolating a first production zone from a second production zone, wherein the first production zone is axially above the second production zone; and monitoring a condition of the first production zone.
 13. The method of claim 12, further comprising: recording the condition of the first production zone; and retrieving the downhole tool monitoring tool from the wellbore.
 14. The method of claim 12, further comprising: communicating the condition of the first production zone to a surface of the wellbore, wherein the communicating occurs in real time.
 15. The method of claim 12, further comprising: producing a fluid from the second production zone while the condition in the first production zone is monitored.
 16. The method of claim 15, wherein the fluid is at least one of a hydrocarbon and water.
 17. The method of claim 15, wherein substantially none of the fluid produced from the second production zone is exposed to the first production zone.
 18. The method of claim 12, wherein the isolating comprises: expanding radially a first sealing element disposed around the downhole monitoring tool, wherein the first sealing element is located between the first production zone and the second production zone; and expanding radially a second sealing element disposed around the downhole monitoring tool, wherein the second sealing element is located above the first production zone.
 19. The method of claim 12, wherein the condition of the first production zone comprises at least one of a temperature, a chemical composition, and a pressure.
 20. The method of claim 10, further comprising: producing selectively from the first production zone. 